data_fabric 1.2 supports ActiveRecord 2.0 and 2.1 through the exact same code as data_fabric 1.1 except refactored to load only when those two versions are detected. If ActiveRecord 2.2 or greater is detected, the new proxy code is used. The new proxy works on a per-class basis and overrides the four class methods which make up the public connection API on ActiveRecord::Base:

This proxy is thread-safe in that its mutable state is stored in thread-local variables. Note the latter two methods aren't implemented, for reasons you can see. remove_connection would be nice to implement but since we don't use it at FiveRuns, I didn't see any immediate need for it. I would happily accept patches for it.